docs: def spliceX(self):
          """
          Return a copy with the x values preferred for ambivalent locations.
          ::
  
              >>> l = Location(pop=(-5,5))
              >>> l.spliceX()
              <Location pop:-5 >
          """
          new = self.__class__()
          for dim, val in self.items():
              if isinstance(val, tuple):
                  new[dim] = val[0]
              else:
                  new[dim] = val
          return new